1. Field of the Invention
The present invention provides a cooling device for a projection device, and more particularly, to a cooling device that can generate and guide airflow of various intensities to cool the lamps.
2. Descriptions of the Related Art
Power levels have increased to accommodate the increased improvement of projector luminance. As a result, lamps may generate intensive heat during operation, which produce hot gasses that are concentrated in the upper area of the lamps. To solve the problem of overheating, a cooling device is usually disposed inside the projector to cool the lamp to reduce the damage to the internal parts caused by excessively high temperatures.
As shown in FIG. 1A, the cooling device 2 of a projector 1 of the prior art comprises a blower 20 in combination with an airflow guiding plate 21 and is adapted to generate an airflow 201, an airflow 202 and an airflow 203 towards the front end 11, lamp wick 12 and back end 13 of the lamp 10 respectively. With further reference to FIG. 1B, when the projector 1 is used upright (e.g., on a table), hot gasses inside the lamp 10 are concentrated towards the first sidewall 101 so that the first sidewall 101 of the lamp 10 is at a higher temperature and the second sidewall 102 of the lamp 10 is at a lower temperature. Because the blower 20 is located above the lamp 10, the airflows 201, 202 and 203 generated by the blower 20 can cool the temperature of the first sidewall 101 of the lamp 10 easily. However, although this can make the temperature difference between the first sidewall 101 and the second sidewall 102 of the lamp 10 relatively small, it is still not enough to cool down the temperature of the high-power lamp 10. Moreover, as shown in FIG. 1C, when the projector 1 is used upside down (e.g., hung from a ceiling), the hot gasses inside the lamp 10 are concentrated toward the second sidewall 102 so that the second sidewall 102 of the lamp 10 is at a higher temperature and the first sidewall 101 of the lamp 10 is at a lower temperature. Because the blower 20 is located below the lamp 10, the airflows 201, 202 and 203 from the blower 20 are unable to cool the second sidewall 102 of the lamp 10 directly, which results in an increased temperature difference between the first sidewall 101 and the second sidewall 102 of the lamp 10 instead. The undue temperature difference has a serious effect on the service life of the lamp 10; furthermore, when a high-power lamp is used, the rotating speed of the blower has to be increased to lower the temperature of the lamp, and this will lead to excessive noise.
To overcome the shortcomings of using a single blower, the cooling device 2 of another projector 1 of the prior art adopts a dual-blower framework to tackle the problem of high temperatures in the lamp 10. As shown in FIG. 2A, the blower 20 is used in combination with the airflow guiding plate 21 and generates the airflow 202 and the airflow 203 towards the lamp wick 12 and the back end 13 of the lamp 10 respectively; and the other blower 22 is used in combination with an airflow guiding plate 23 and generates an airflow 221 towards the front end 11 of the lamp 10. This framework can desirably lower the temperature of a high-power lamp. With further reference to FIG. 2B, when the projector 1 is used upside down (e.g., hung from a ceiling), the front end 11 of the lamp 10 can still be desirably cooled by the airflow 221 of the blower 22 without being affected, but the hot gasses inside the lamp 10 are concentrated towards the second sidewall 102 of the lamp 10 so that the second sidewall 102 of the lamp 10 is at a higher temperature and the first sidewall 101 of the lamp 10 is at a lower temperature. In addition, the blower 20 is located below the lamp 10, so neither the airflow 202 nor the airflow 203 of the blower 20 can cool the second sidewall 102 of the lamp 10 directly. Consequently, the temperature difference between the first sidewall 101 and the second sidewall 102 of the lamp 10 increases and leads to a non-uniform temperature distribution at the filament 12 and the back end 13, which also has an adverse effect on the service life of the lamp 10.
In view of this, an urgent need exists in the art to provide a solution that can not only reduce the temperature of the front end and the wick of a lamp effectively, but also minimize the temperature difference between the upper side and the lower side of the lamp by controlling the intensities of airflow no matter how the projector is used.